Method of ore separation



Patented Sept. 18, 1934 TES METHOD OF ORE SEPARATION Joseph P. Ruth, Jr., Denver, 0010., assignor to The Ruth Company, Denver, 0010., a corporation of Colorado No Drawing. Application August 23, 1932, Serial No. 630,092

4 Claims.

This invention relates to improvements in the froth flotation treatment of ores.

The object of this invention is to materially improve the recovery of the copper minerals in their copper concentrates, or any other mineral, the surface film of which is soluble in an ammoniacal solution. I have found that in treating complex ores containing pyrrhotite, pyrite, copper, zinc and iron sulfide, by a method of inhibiting by means of Zinc cyanide, a particularly strong depressing action is effected on the chalcopyrite and upon copper minerals generally by the precipitation, I believe, of a film on the surface of the chalcopyrite at the same time that the zinc sulfide and iron sulfide are depressed by the same chemical in much the same manner. In using this chemical to depress, it is naturally necessary when the time comes to float, to promote the particular sulfide with some chemical which will not promote the other sulfides. I have found ammonia to be particularly suitable for this purpose because the zinc cyanide coating on copper sulfide is soluble in ammonia, but the zinc cyanide coating on sphalerite is not soluble, nor is the zinc cyanide coating on iron pyrite scluble, in ammonia. Ammonia, then, in conjunction with Zinc cyanide, is a very valuable promoter. Take its action, for example, on Buchans ore from Newfoundland, which contains lead sulfide, chalcopyrite, sphalerite and iron pyrite. By conditioning this ore properly with zinc cyanide, the chalcopyrite, sphalerite and pyrite are all inhibited to the extent that they float with little or no activity; whereas, the lead sulfide has not been inhibited; in fact indications seem conclusive that cyanide is very beneficial, either the insoluble or soluble kind, in suspension or solution when lead sulfide is to be floated, indicating that any films which might obstruct the lead sulfide from attaching to a bubble are removed by the cyanide making a clean lead sulfide surface and a very active, rapid floating condition for lead sulfide. After the lead sulfide has been removed from this pulp, it becomes necessary to revivify or promote the flotation of the copper sulfide minerals, in this case chalcopyrite, and at the same time not promote, or, in a few words, not clean the surfaces of the sphalerite or iron pyrite, by the use of a chemical which will dissolve the film from the chalcopyrite, and if possible, maintain a precipitating condition on the sphalerite and on the pyrite. This is effected by ammonia. The addition of a satisfactory quantity of ammonia renders the coating on the chalcopyrite soluble which results in perfect flotation of the chalcopyrite while maintaining perfect inhibition of the zinc and the iron. After the copper has been removed, the zinc is promoted and floated with copper sulfate in the well known manner.

As an example of my method let us take a complex ore containing lead sulfiide, chalcopyrite sphalerite and iron pyrite. After the ore is ground; it is conditioned with zinc cyanide which inhibits the chalcopyrite, the sphalerite and the pyrite, but does not have any inhibiting action on the lead sulfide which can therefore be removed by subjecting the pulp to froth flotation treatment. After the lead sulfide has been re moved the chalcopyrite is promoted by the addi tion of ammonia in sufficient quantity to dissolve the inhibiting film. The copper sulfide is now removed by subjecting the pulp to froth flotation treatment, after which the zinc is promoted by adding copper sulfate and subjecting the pulp to froth flotation treatment thus leaving only the iron pyrite.

As a specific example let us take one ton of Bachans ore from Newfoundland, which contains lead sulphide (PbS) chalcopyrite (CuFeSz), zinc sulphide (ZnS) and iron pyrite (F682). The ore is ground in water until the requisite fineness has been attained and is then conditioned for a period of about fifteen (15) minutes with zinc cyanide, Zn(Cn)2 about one-half of a pound being used. Cresylic acid and a disubstituted dithiophosphate commonly referred to as aerofloat 25, about two-tenths of a pound of each is now added and the ore subjected to froth flotation whereby the lead sulphide is removed. Ammonium hydroxide (NI-140E) is now added in an amount of about three-tenths of a pound and the ore conditioned for about five minutes, whereby the chalcopyrite is revivified and is then removed by froth flotation. The zinc sulphide is now revivified by adding about eight-tenths of a pound of copper sulphate (011304) and one pound of calcium hydroxide, Ca(OH)z, and after conditioning for about five minutes the ore is again subjected to froth flotation whereby the zinc is removed leaving only the pyrite and the gangue.

What I claim is:

1. In the differential separation of complex sulfide ores, the steps of inhibiting one or more of the sulfides with zinc cyanide and adding ammonia to dissolve the film from the surface of one of the inhibited sulfides, and subjecting to the froth flotation treatment for the separasulfide ores by froth flotation, the steps of adding zinc cyanide whereby one or more of the sulfides are inhibited, subjecting the pulp to froth flotation whereby any sulfide that has not been inhibited will be separated, adding ammonia to dissolve the film from the surface of one of the inhibited sulfides, and subjecting the pulp to the froth flotation treatment for the separation of the sulfide so promoted.

3. In the difierential separation of complex sulfide ores containing chalcopyrite, sphalerite and iron pyrite, the steps of adding zinc cyanide whereby ail of the sulfides are inhibited, adding 

